Brake shoe for railway cars



Oct. 19, 1937. J, L, KARR 2,096,430

v BRAKE SHOE FOR RAILWAY CARS 1 Filed Au'g. 26, 1936 2 Sheets-Sheet l INVENTOR James L Karr- Patented Oct. 19, 1937 UNITED STATES PATENT OFFICE James L. Karr, Portland, reg., assignor to The American Brake Shoe and Foundry Company,

Wilmington, DeL, a

corporation of Delaware Application August 26, 1936, Serial No. 97,983

- 6 Claims. 'My invention relates to brake shoes suitable I for use on railway cars.

One of the main causes of fracture of the cast iron lining of a brake shoe, as customarily made, :.is due to the structural form of the steel back. This, when made in the customary form of a channel bar, is not sufficiently capable of absorbing heavy shocks, and. consequently transmits them to the surrounding cast iron lining, 1 and, besides, frequently is distorted by frictional heat, engendered in application of the brake shoe; and, in consequence, undue stresses are set up, which result in fracture of the cast iron lining, and in the detachment of the broken portions thereof from the steel back, causing the dropping off of parts of the shoe lining, rendering the brake shoe unfit for further service.

While a certain amount of flexibility is essential, on the other hand, if necessary strength is sacrificed, the reinforcing back of the brake shoe becomes too yielding, and is not efficient in service.

The object of my'invention is to produce a brake shoe which combines the essential flexibility with the required strength.

A particular object of my inventionis to provide,-in case of fracture of the lining, for the holding of the broken lining pieces firmly in place on the steel back, by means which will prevent their displacement and dropping ofi".

A further object of my invention is to provide a brake shoe of simple constructionand low cost, at the same time having maximum durability.

I attain these objectsby employing in the first place a steel back uniformly curved transversely thruout itslength to its end portions, the end portions being formed so as to provide flat anchoring sections, extending parallel with the wearing surface of the shoe, in compliance with the present-day requirements of brake shoes. The curved section and end portions combine to provide a steel back of ample flexibility but having required strength. I consider the curving 5 of the back uniformly, transversely, describing an arc whose center is located in the body of the lining, a superior and more efficient shape for the steel back of a brake shoe.

I further provide at both ends of the said .curved section of the back, lining-holding lugs which project at converging angles from the inner face of the back into the cast iron lining.

These lugs I consider of great value in themselves, even tho the steel back be of the customary channel form. Thus, in case of the fracture of the cast iron lining of my brake shoe, the broken lining pieces are restrained against longitudinal movement outward by said holding lugs, andthe abutment of the inner ends of the broken pieces against each other prevents their longitudinal inward movement on the steel back, while the transverse curving of the steel back prevents their lateral displacement. Thus, upon the fracture of the lining, the construction provided by my invention will still hold the broken portions of the cast iron lining in place so securely that the brake shoe may be continued in service until it is convenient to replace the brake shoe.

The structural details of my invention, by which I attain the advantages above described, are hereinafter fully set forth with reference to the accompanying drawings, in which:

Fig. 1 shows a perspective view of the steel back of my improved brake shoe looking at the outer side;

Fig. 2 is a similar perspective view looking at the inner side of the steel back;

Fig. 3 is a side elevation, half in longitudinal section, the section being taken on the line 33 of Fig. 4; and

Fig. 4 is a transverse section taken on the line 4'-4 of Fig. 3.

The back I is made of rolled spring steel, pressed or otherwise formed. According to the preferred form of my invention, this back is shaped so as to have a continuous, transversely, uniformly curved section 2 thruout its length, that is, extending to its end portions 3, 3a Preferably, I form such curve so as to describe approximately an arc whose center is located in the 3 body of the cast iron lining which is attached to the steel back. Said end portions 3, 3a are formed so as to provide flat anchoring sections, which merge into the said curved section 2, at 4 and 4a, respectively, and extend parallel with the wearing surface of the shoe, in compliance withthe requirements of the present-day brake shoes.

Adjacent the ends of the curved section 2 of the back I provide lining holding lugs H], l l Openings are provided in the back as at 5, 6, l, 8 and 9 thru which the cast iron lining may enter and thus become locked with the steel back. The openings 8 and 9 are stamped out so as to provide the holding lugs Ill and II projecting at converging angles from the inner face of the back into the cast iron lining l2 of the shoe. These lugs l0 and II are of great value, as already mentioned, in case of fracture of the cast iron lining of my brake shoe, and, in such case,

function to restrain the fractured lining pieces against longitudinal, outward movement, while the abutment of the inner ends of the pieces against each other prevents their longitudinal inward movement on the steel back. At the same time, the transverse curving of the middle section 2 of the back cooperates to prevent the lateral displacement of the fractured lining pieces. Hence, when fracture of the cast iron lining of my brake shoeoccurs, the described construction will still hold the pieces in place so securely that the brake shoe may be continued in effective service until it is convenient to replace the broken shoe by another.

The said lugs [0, ll would perform their described function also in conjunction with the steel back transversely arched, for example, to'

channel form. But I consider the curving of the steel back, as above described by me, decidedly preferable; because, in my opinion, a steel back made in the form of a channel bar is incapable of absorbing heavyshocks to which the brake shoe is more'or less subjected in service; and,'furthermore, is liable to become distorted by the frictional heat produced in the application of the brake shoe to the car wheel.

The middle portion of the curved section 21 is slightly recessed as at l3 and is engaged by a' strap l 'i having its ends bent in as at I5; the strap i l functioning in the usual manner. Other details of my brake shoe not described serve their customary purpose. v

Without limiting myself to the precise embodiment of my invention as illustrated in the accompanying drawings, What I claim is:

1. In a brake shoe of the character described, a steel back having a middle section transversely arched thruout its length, the end portions of said back flattened to provide anchoring sections merging with said middle section, lugs projecting at converging angles from the inner face at the opposite ends of said middle section into the brake shoe lining, whereby, in case of fracture of the brake shoe lining, said lugs prevent out-' ward longitudinal movement of the brake shoe lining from said back and said transverse arch of the middle section prevents lateral movement of the lining from said back, the middle portion of said middle arched section of said back being slightly recessed at the edges, and a strap of inverted U-shape having its extremities bent and engaging said recessed edges.

2. In a brake shoe of the character described, a steel back having a middle section transversely arched thruout its length, the end portions of said back flattened to provide anchoring sections merging with said middle section, lugs projecting at converging angles from the inner face at the opposite ends of said middle section into the brake shoe lining.

3. In a brake shoe of the character described, a steel back having a middle section uniformly, transversely curved thruout its length, the end portions of said back flattened to provide anchoring sections merging with said middle section, lugs projecting at converging angles from the inner face at the opposite ends of said middle section into the brake shoe lining.

4. In a brake'shoe of the character described, a steel back having a middle section uniformly, transversely curved thruout its length to approximately an arc whose center lies in the body of the brake shoe lining, the end portions of said back flattened to provide. anchoring sec,- tions merging with said middle section, lugs projecting at converging angles from the inner face at the opposite ends of said middle section into the brake shoe lining.

5. A steel back for a' brake shoe having a middle section transversely arched thruout its length, the end portions of said back flattened to provide anchoring sections merging with said middle section, lugs projecting at converging angles from the inner face at the opposite ends of said middle section.

6. A steel back for a brake shoe having a middle section uniformly, transversely curved thruout its length to approximately an arc whose center lies in the body of the brake shoe lining, the end portions of said back flattened to provide anchoring sections merging with said middle section, lugs projecting at converging angles from the inner face at the opposite ends of said middle section.

JAMES L. KARR. 

